In an ink printing system, ink generally is delivered from an ink supply to a printing mechanism such as an inkjet printhead. In some systems, the ink supply and printing mechanism may be integrated with one another in a unitary package or module. The ink supply and printing mechanism in other systems are manufactured as discrete components to enable the ink supply to be separately replaced or replenished without removing the printing mechanism. In either case, the delivery of ink from the ink supply to the printing mechanism requires careful control. In particular, the volume and pressure of ink delivered to the printing mechanism must be controlled to avoid flow irregularities that can cause artifacts and degrade image quality.
Excessive static pressure, for example, can cause undue wetting that saturates the nozzle plate of an inkjet printhead during an inactive period. Excessive wetting at the nozzle plate can adversely affect the jetting characteristics of the inkjet printhead, causing imprecise jetting of the ink droplets to the print medium or preventing jetting altogether. At the same time, ink consumption is increased, requiring more frequent replenishment or replacement of the ink supply. Moreover, maintenance of consistent static pressure can be undermined by the physical characteristics of different inks, print mechanisms, or print media. Accordingly, ink delivery pressure control remains a challenge in the design of an ink printing system.